1. Field of the Invention
The present invention relates to jet engines, and more specifically, to a self-starting turbineless jet engine that includes fuel delivery, fuel combustion, and corresponding airflow constraints, but which incorporates no turbines or other moving parts other than those associated with the fuel delivery.
2. Description of the Related Art
While jet engines employing turbines have received both long-term and widespread adoption for both commercial and military aviation applications, other jet engines, such as ramjet engines with no internal moving parts beyond their fuel delivery systems, have not seen widespread adoption. Note that as used herein, the term “ramjet” is taken to including sub-sonic, sonic and supersonic RAM jet engines unless designated otherwise.
A ramjet uses its own forward motion to compress incoming air without a turbine or other rotary compressor. When a ramjet is moving at sufficiently high speed through air, the physical configuration of the ramjet creates a high pressure region in front of the engine and a corresponding low pressure region to the rear of the engine, leading to a large pressure differential. This large pressure differential forces air into a tube within the ramjet where internal constraints on airflow cause the air to be compressed. The compressed air is ultimately combusted with fuel and released to the rear of the engine to provide thrust. A variety of liquid and solid fuels can be used as long as those fuels combust sufficiently well to maintain the necessary airspeed for continuous ramjet operation.
Modern materials, manufacturing techniques and design simulations have reached a level of sophistication sufficient to produce workable ramjet engines. Furthermore, ramjets can outperform turbine-based jet engine designs at certain supersonic speeds and are more fuel efficient than rockets over much of their working range. The performance of ramjet engines exceeds that of turbine-based jet engines, in part because the extreme temperatures and pressures associated with supersonic travel place severe demands on rotating turbine blades, while ramjets do not have turbines or comparable moving internal parts. However, current ramjet engines have other limitations that do not exist with turbine-based jet engines.
A typical ramjet design relies upon the internal pressure differential produced by a shockwave developed within the engine as air passes from supersonic to subsonic flow. This is achieved by carefully shaped and contoured surfaces within the engine, which accelerate and decelerate the airflow as desired. The result is an engine that is capable of producing useful amounts of thrust at high speed, including supersonic speeds, with no moving parts. However, current ramjet engines are severely limited because they cannot produce thrust at zero airspeed, and thus cannot move an aircraft from a standstill. As a result, ramjet engines require some other form of propulsion to provide the requisite minimum air velocity for operation. Because the other form of propulsion incurs its own costs and issues, ramjets have not been seen as practical for many civilian and military applications. There is a need for a turbineless jet engine that can produce thrust from a standstill so that no additional form of propulsion is required. Thus, a self-starting turbineless jet engine solving the aforementioned problems is desired.